Process of preparing electrolytes for use in the deposition of a metal or metallic alloy.



7 subject of the King of Italy, and resident offsmiles PATENT ornron.

'rAscA'L'MARmo, or LONDON, ENGLAND.

PitocEss-or PREPARING-'EIJECTROLYTE'S 'ro'n usn'm rnn on MET&ELIC':ALLOY..

DEPOSITION or A METAL No Drawing.

Specification of Lette'rs Patent. Patefited' Sept, 16,1913 H -gpplication'filed October 29, 1912. Ser'ial'No. 728,400.

To all whom it may concern: if V 1 -'Be 'it---known that I, PASCAL Manmo, a

129 Albert street, Park street, London, N. W., England, professor of chemistry, have invented a certain new and useful Process of Preparing Electrolytes for Use in the Dep-' osition of a vMetal or Metallic Alloy, of which the following is a specification.

The object of the present invention is to facilitate the electro-chemical reduction of soluble metal salts into ions by dissociating said salts 'as completely as possible in order to subsequently electrolytically deposit the metal present in said salts on metallic or met-allized surfaces, and to produce alloys such-as those of nickel'and silver'or of tin and copper (bronze) by the simulta- -their extensive use in neous electrolytic deposition of the metals I refer more particularly to these alloys as they are of con-- siderable commercial importance owing to the arts, their dura bility, and-the resistance they offer to atmospheric influences. I 'fected by submitting the-solution of the steps, viz :'(a)

This disassociation is efsalts to the herein'described process which is constituted by three following successive I add to a solution of the salt or salts of the-metal or metals to-be deposited, an organic reducing agent which serves to efiect the partial dissociation of the metallic salt or salts, (b) I then, heatthe; solution in order to assist in the dissocia-, tionby decreasing the cohesion of the molecules and thus overcoming'certain aflinities irreducible at ordinary temperatures. (a)

When the solution has become 'cold'I add to it another reducing agent for thepurpose of effecting dissociation to a maxlmum 'degree, that is,-as far-as'may be without altering thefact of solution.

Owing 'to the dissociation of the soluble metal salts these salts are resolvedinto ions which serve as current carriers.- 'When the dissociation 'hasbe'en effected the molecular conductivity of the-electrolyteiis-at itsmaxie mum, l-and hence it-is easy toefiec'tthe-reduo "-tion offth'e solution for;

the electrolyte by a relatively eakcurrent,..(a ;only solu- ;-t ions containing ions are conductors of electiricityd and to obtam' a metallic,

V Y homogeneous, electrolytic deposit which tenaciously adheres to the cathode.

As regards the organic reducing agents it is necessary to employ an organic acid I the stability of the electrolyte. As reducing agent during the first step of the process I prefer to employ magnesium borocitrate in solution. As regards the reducing combined with a fixed base in order to assure agent during thelast step of the process -I prefer to employ either .glucoscitric or gluco-tart-aric acid inthe proportion of 15% of the weight of the metal salt or salts. Gluco-citric acid may be prepared by mixing together 1 molecular Weight of glucose and 3 molecularweights Of CltIiC acid, and gluco-tartaric acid' by mixing together 1 molecular weight of glucose and, 2'molecu1ar weights of tartaric acid.

In carrying out my invention, it is'necessary to'select a salt of the metal to be deposited which will become wholly dissolved in the electrolyte and yield apure metallic de osit.

t' is to be understood that my invention is'not limited to the deposition of any particular metal ormetallic alloys and I will now refer to certain metals by'wa'y-of'e'xto avoid mixing with the magnesium borocitrate solution, metallic solutions which would, when in presence,'decompose (meanother and form an insoluble compound.

Inasmuch as potassium 'cyanid is a so1- vent for old, silver, nickel, and copper, there shouId be employedwhen these'metals or their alloys are to be-deposited either gold, silver, nickel or copper cyanid of potassium salts. For depositing iridium I prefer to use iridium chlorid, as a solution ofthis salt yields" by electrolysis apure metallic deposit. For :depositing palladium, it is necessary to employ palladium-chlorid which I dissolve in ammonia to form pal ladium ammonium-ch orid For de ositing rhodium, I prefer to employ .rho ium soample and to'the salts of'these metals which dium-chlorid. For depositing platinum, it I is preferable -to use'a solution-of; potassiuim .platinate. 5 This solution should-be so Iperfectly iieutral that, when diluted in dis- A twitsrfystzilline so rapid that it is almost impossible to'obtliin a no sit. of the metal in a ductile and malleable state. For depositing tin I prefer to employ tin sulfate dissolved in aluminium sulfate neutralized .by barium chlorid. For depositing iron I prefer to employ iron prqtqcl lopigl which W&l%tl-t -FOHlPOS1l1I1 g cadiium or zinc I prefer to employ ammoniumsulfate salts of said metals in order to obtain a malleable and ductile deposit. A solution of the salts of these metals possesses high conductivity and zinc or cadmium anodes dissolve in it very easily. For depositing lead I prefer to employ a lead salt dissolved in ammonium tartrate in order to obtain a homogeneous metallic deposit. For depositing tungsten, it is necessary first to prepare a solution of an alkaline tungstate and then to pour it drop by drop into diluted nitric acid. The tungsten compound thus obtained is then dissolved in ammonium tartrate mixed with potassium or sodium phosphate.

'. For depositing chromium, there must be employed chromium sulfate dissolved either in potassium or aluminium sulfate. For depositing molybdenum I prefer to employ ammonium phosphomolybdate dissolved in potassium hydroXid.

The organic reducing agent first employed should in all cases be capable of remaining unaifected by heat.

In order .to obtain the simultaneous electrolytic deposit of an alloy, the electrolyte may be prepared by treating a mixture of the metals according to the method above set forth, or by treating each metal sepa-' rately to obtain separate electrolytes and afterward mixing the electrolytes together. In this connection I would state that com sideration must be given to the relative pro portions of the individual metals necessary toobtain the desired alloy, to the law of precipitation of each individual metal, and to the amount and density of current necessary for satisfactorily depositing a stated quantityv of metal per ampere-hour which depend on the electro-chemical equivalency of each metal. As the electrolytes for depositing alloys are similarly prepared, a mixture of them will be of a stable nature and will not form an insoluble product.

It is obviously unnecessary to give directions regarding the actual deposition process as this in no way varies from current practice.

When in the appended claims I speak of glued-citric acid, I desire to include also its well-known equivalents, such as gluco-tarlyte for use in the deposition of a wl,

which consists in firstmaking suitable aqueous solution containing a salt of the metal to be deposited, then adding a suitable organic reducing agent to the solution, then heating the resulting liquid, and finally, when said liquid has cooled, adding to it a suitable organic reducing agent, substantially as and for the purpose described.

2. The process of preparing an electrolyte for use in the deposition of a metal, which consists in first making a suitable aqueous solution containing a salt of the metal to be deposited, then adding magnesium-borocitrate to said solution, then heating the resulting liquid, and finally, when said liquid reducing agent, substantially as and for the purpose described.

3. The process of preparing an electrolyte for use in the deposition of a metal, which consists in first making a suitable aqueous solution containing a salt of the metal to be deposited, then adding a suitable organic reducing agent to the solution, then heating the resulting liquid, and finally, when said as and for the purpose described.

t. The process of preparing an electrolyte for use in the deposition of a metal, which consists in first making a suitable aqueous solution containing a salt of the metal to be deposited, then adding magnesium borocitrate to said solution, then heating the rehas cooled, adding to it a suitable quantity of gluco-citric acid, substantially as and for the purpose described.

5. An electrolyte for use in the deposition of a metal, comprising a solution containing a salt of the metal to be deposited, said saltbeing dissociatedtoa maxium degree into ions by the treatment of a, suitable aqueous solution containing said salt with a suitable organic reducing agent, then heating the resulting liquid, and finally, when has cooled, adding to it a suitable organic liquid has cooled, adding to it a suitable quantity of gluco-citric acid, substantially sulting liquid, and finally, when said liquid said liquid has cooled, adding to it a suitable organic reducing agent, substantially as and for the purpose described.

6. An electrolyte for use in the deposition of a metal, comprising a solution containing a snlt of the metal to be deposited, Said salt being dissocinted to a lllllXllHlllli degree into ions by the treatment of a suitable aqueous solution containing said salt with nmgne- 1 sium lmro-eitriite, then heating the resulting liquid, and finally, when said liquid has cooled, adding to it n. ,suitublc quantity of gluon-citric acid, substantially as and for the purpose dencribed. PASCAL MAILING.

Witnesses WILLIAM DAVIES, O. J Wouul. 

